[cltmmm]

Thanks for the reply, and sorry for the delay. I lost track of the forum...

A quick background of the vehicle. I bought it used from a shady dealer (found that out later he was a scheister). It had 67k miles on it and it threw an O2 sensor code after I got it home. I replaced one bad O2 sensor. About 200 miles later it started throwing the 0420 and 0430 codes. When I took it into the dealer, they said I need a new converter. I don't know how much I believe them...

I SeaFoamed the engine through the vacuum system and it got rid of the code for about 2,000 miles. Now it is back with a vengeance. I put 50k miles on a year so I am at 170k miles now in two years and need to get the car inspected (emissions are tested).

My thought is they ran it with a bad O2 sensor so long they burnt out the cat. I have SeaFoamed it again, but it no longer fixes the problem. I am wondering if changing all the O2 sensors will help if the cat is bad anyways...

In any case, what is a good O2 sensor to get on the cheap?

Thanks!